Grinding and polishing table unlocking device



May 19, 1959 FIG! v. s. FIRESTONE GRINDING AND POLISHING TABLE UNLOCKINGDEVICE Filed Dec. 2, 1957 2 Sheets-Sheet 1 Fla. 2

:1) d BY E INVENTOR.

y 19, 1959 .v. s. FIRESTONE GRINDING AND POLISHING TABLE UNLOCKINGDEVICE Filed Dec. 2, 1957 2 Shets-Sheet 2 I INVENTOR. m/vae' .s.F/AE'Sfd/V' arrow/5x GRINDING AND POLISHENG TABLE UNLOCKING DEVICE VanceS. Firestone, Ford City, Pa., assignor to Pittsburgh Plate GlassCompany, Allegheny County, Pa., a corporation of PennsylvaniaApplication December 2, 1957, Serial No. 700,211 Claims. (Cl. 51-240)This invention broadly relates to grinding and polishing plate glass,and more particularly to apparatus for automatically unlocking adjacenttables which support sheets of plate glass for grinding and polishingoperations.

In the manufacture of polished plate glass, rough rolled glass is cutinto discrete sheets and each sheet is embedded in plaster of Paris on awheeled table adapted to run on tracks along a grinding and polishingline. Adjacent tables are locked together to present the sheets of glassto the grinding and polishing runners. At the end of the grinding andpolishing line the end table is unlocked from the adjacent table and theglass sheet thereon is removed, thereby making the table available forreceiving another sheet to be ground and polished through the line.Heretofore, the unlocking of the end table from the adjacent one hasbeen manually done, a relatively dangerous operation. The presentinvention provides apparatus for dispensing with the manual unlocking ofadjacent tables,

the apparatus being constructed in such a manner that the unlocking ofthe tables occurs at the end of the grinding and polishing line underthe control of the tables as they move toward the end of the line.

Therefore, the primary object of this invention is the provision ofapparatus for unlocking adjacent grinding and polishing tables.

Another object of this invention is the provision of apparatus forautomatically unlocking an end table in a grinding and polishing linefrom an adjacent table, the unlocking being controlled by the tables asthey move toward the end of the line.

These and other objects and features of this invention will be apparentfrom the following description when taken with the accompanying drawingsin which:

Figure l is an elevational view showing grinding and polishing tablesand the mechanism for unlocking adjacent tables;

Figure 2 is a sectional partial view of the apparatus of Figure 1 takenon line 22 of Figure l and reduced in size;

Figure 3 is a sectional partial View of the apparatus of Figure 1 takenon line 3-3 of Figure 1 and reduced in size;

Figure 4 is an enlarged view, partially in section, showing the lockingmeans; and

Figure 5 is a schematic illustration of the pneumatic system of thisinvention.

Referring to the drawings, and especially to Figures 1, 2 and 3, thereis illustrated a plurality of grinding and polishing tables lockedtogether for movement to the left, as viewed in Figure l, for receivingand conveying plate glass sheets along the line, the tables shown beingadjacent the end of the grinding and polishing line and beingidentified, for purposes of description as 10A, 10B and 100, the table10C being the last one in the line and being described as the oneunlocked from the line. The tables 10 are identical and of suitablechannel construction having transverse webs, as may be easily viewed inFigure 4. The tables 10 are each provided with the itedl States Patent 0usual wheels, not illustrated for the sake of clarity, which run onlongitudinal tracks 12 supported above the floor by means oflongitudinal I beams 14, (see Figures 2 and 3). The adjacent tables 10are locked to one another by means of a locking mechanism, generallyidentified by r the reference character 16, and shown in detail inFigure 4.

Each locking mechanism 16 comprises a portion received within thetrailing end of a table 10 and a cooperating portion received within theleading end of a table 10. The parts to be described are preferablyduplicated transversely of the table and, since their construction isidentical, one description will suflice. The portion of the lockingmechanism received in the trailing end of a table includes a latchingjaw element 18 resiliently mounted for limited longitudinal movement andhaving an upstanding engaging flange or jaw 19 extending beyond the endof the table for cooperation with the portion received within theleading edge of the adjacent table. The latching element 18 is providedwith a jaw insert 20 attachedto the engaging flange 19, the outerextremity of which is provided with a curved surface thereon. Theelement 18 is attached or made integral with a longitudinally disposedthreaded rod 22 supported for sliding motion by means of spaced,cylindrical bushings 24 and 26. The bushings 24 and 26 are retainedwithin a housing 28 fixed within the table 10 and provide a cavity 30 toreceive resilient means in the form of a pair of relatively strongcompression springs 32 and 34. The compression springs 32 and 34surround the rod 22 and are positioned between a wall of the housing 28and a substantial- 1y cylindrical spring stop 36 threadably received onthe rod 22. The resilient means urge the element 18 toward the right, asillustrated in Figure 4, and the resilient force may be adjusted bymoving the spring stop 36 to the right or to the left. In the actualconstruction the physical size of the resilient means dictates the useof a pair of compression springs, but it is to be understood that asufficiently strong single spring could be used without departing fromthe spirit of this invention.

The portion of the locking mechanism 16 received within the leading endof the table 10 includes a latching jaw element 38 having a dependingengaging flange or jaw 39 to which is fixed a jaw insert 40. The insert40, like the jaw insert 20, is provided with a curved surface adapted tocooperate with the jaw 20 carried. by the locking element 18 when theadjacent tables are locked together as indicated in full lines in Figure4. The curved surfaces of the jaw 20 and 40 allow smoother engagementand disengagement of the latching elements 18 and 38, as will beapparent to one skilled in the art. The latching element 38 is suitablyfixed, as illustrated, to a transversely extending shaft 42 rotatablyjournaled in spaced substantially cylindrical bushings 44 carried by thetable 10 in any conventional manner.

An operating arm 46 rotatably carrying a roller 48 at its lower terminalend is provided for moving the latching elements 18 and 38 into and outof their latching position so that, as illustrated in Figure 4, when thearm 46 is in its full line position the adjacent tables 10 are lockedtogether, and when the arm 46 is in its dotted line position thelatching elements 18 and 38 are disengaged and the adjacent tables areunlocked from one another. The arm 46 is eccentrically fixed to theshaft 42 in such a manner that a central longitudinal axis thereofpasses through an axis 50 of the shaft 42, the axis 50 being displacedfrom the major axis 52. The displacement of the axes 50 and 52 allow thearm 46 to move through a much greater are than that of the latchingelement 38, this being apparent from the full and dotted line positionsof the arm 46 and the full and dotted line positions of the element 38,as illustrated a in Figure 4. The rotation of the latching element 38 islimited by stop surfaces 54 and 56, and the rotation of the arm 46 islimited by stop surfaces 58 and 60. The stop surfaces just described aredefined on a casting 62 suitably connected within the table 10.

A. pair of spaced limit switches 64 and 66 are supported beyond thesides of the tables 10 along the path of movement of the tables and theswitches are provided with depending switch levers 68 and 70,respectively. A vertically disposed and movable cam rod 72 having a camsurface 74 thereon is provided for actuating the limit switch 64 byallowing the switch lever 68 to move off the cam surface 74. The cam rod72 is pivotally connected to a link 76 fixed to a transversely extendingshaft 78, the shaft 78 being rotatably supported in spaced bearings 80,as illustrated in Figure 2. Operating levers 82 are fixed to the shaft73 in transverse alignment with the arms 46, previously described, andsuch levers may be provided with hardened wear surfaces, such as shownin Figure 1, if desired.

In a like manner a vertically disposed and movable cam rod 84 having acam surface 86 thereon is provided for actuating the limit switch 66 byallowing the switch lever 70 to move off the cam surface 36. The cam rod84 is pivotably connected to a link 88 fixed to a transversely extendingshaft itl supported in spaced bearings (not shown) which are similar tothe bearings 80. Operating levers 92 are fixed to the shaft intransverse alignment with the arms 46 and the levers may be providedwith hardened wear surfaces, if desired.

A truck or sled 94 disposed for limited rolling motion on spaced rails96 is positioned beneath the tables 10 near the end of the line, and thetruck 9 is provided with a suitably journaled rotatable shaft 98 towhich is fixed bars or the like 100 for cooperation with the arms 46.Counterweights 102 disposed adjacent the outer side extremities of thetruck 94 are also fixed to the shaft 88, and stop means 104 are providedon the truck or sled 94. The counterweights 102 position the bars 100 inthe manner illustrated in Figure 1, and abut the stops 104 when the bars100 are so positioned. This construction allows the bars 100 to freelyrotate in a counterclockwise direction, (as viewed in the drawing), aswhen the arms 46 move past the truck 4, and limit their moving in aclockwise direction by the counterweights 92 abutting the stops 94.

A double acting air cylinder 106 is supported on the rail 96 and itspiston rod 108 is attached, as at 110, to the truck or sled 94. Thus,when air is introduced into one end of the cylinder 106, the truck 84will be moved in one direction, and when air is introduced into theother end of the cylinder 106, the truck 94 will be moved in theopposite direction.

Attention is now directed to Figure 5 illustrating schematically thepneumatic system of this invention. Shown are the double acting aircylinders 106, an air pump 112 of conventional design, solenoid valves11 and 116 adapted to be actuated in a manner to be described by thelimit switches 64 and 66, respectively, and conduit, hoses or the like118, 120, 122, 124, 126, 123, 130, 132 and 134.

The conduit 11% is connected to the pump 112 and to each of the valves114 and 116; the conduit 126 is connected to the valve 114 and to theconduit 122, which in turn connects the rear ends of the cylinders 166;the conduit 124 connects the front ends of the cylinders 106 and isconnected to the conduit 126; the conduit 128 is connected to theconduit 126 and to each of the valves 114 and 116; the conduit 13% isconnected to the conduit 120 and to the valve 116; and the conduits 132and 134 are exhaust conduits for the valves 114 and 116, respectively.

With the limit switches 64 and 66 inactivated (as is the switch 66 shownin Figure l), the solenoid valves 114 and 116 are not energized. Thesolenoid valves are .4 so constructed that when not energized, theconduits connected thereto will be blocked and no air flows therein. Thetruck 94, at this time, is in its illustrated posi tion. As the table10A moves past the limit switches 64 and 66, the arms 46 initiallycontact the levers 82 thereby rotating the shaft 78 and, through thelink 76, moving the cam arm 72 vertically upwardly. This movement of thearm 72 allows the switch lever 68 to move off the cam surface 74,thereby energizing the solenoid valve 114. The energization of thesolenoid valve 114 causes the connection of the conduits 113 and and theconnection of the conduits 128 and 132. Air under pressure from the pump112 flows through the conduit 118 and through the conduits 120 and 122into the rear ends of the cylinders 106, thereby moving the pistons andthe connected truck 94 to the left, as viewed in Figure l. The bars 100on the truck 94 contact the arms 46 associated with the lockingmechanism 16 on the table 1013 directly over the truck 94, and move thearms 46 to their dotted line position, thus unlocking the last table 10Cfrom the line. At the same time, trapped air in the front ends of thecylinders 106 exhausts through the conduits 124, 126, 128 and 132.

Further movement of the table 10A brings the arms 46 into engagementwith the levers 92 associated with the limit switch 66, which isactivated in the same manner as the limit switch 64. However, activationof the limit switch 66 energizes the solenoid valve 116, so as to causethe connection of the conduits 118 and 128 and the connection of theconduits 130 and 134. Thus, air under pressure flows through theconduits 128, 126 and 124 into the front ends of the cylinders 106 toact against the pistons and return the truck 94 to its illustratedposition for a subsequent unlocking operation. At the same time, air inthe rear ends of the cylinders 106 is exhausted through the conduits122, 130 and 134. When the table 10A passes the limit switch 66, theswitch is inactivated which deenergizes the solenoid valve 116, thuscompleting an operating cycle.

While this invention has been described with reference to oneembodiment, it is to be understood that this is by way of illustrationand not limitation.

I claim:

1. In plate glass grinding and polishing apparatus, the combination of aplurality of tables for supporting and conveying sheets of glass along agrinding and polishing line and having a path of movement along theline, latching means for connecting adjacent tables together and adaptedto be unlatched near the end of the line thereby freeing the end tablefrom its adjacent table, said latching means comprising a first jawmember connected to each table adjacent at one end and a secondcooperating jaw member connected to each table adjacent the opposite endwhereby a first jaw member of one table engages a second cooperating jawmember of an adjacent table when the tables are latched together, meansmounting the first jaw members for limited arcuate movement from alatching position to an unlatching position, an arm connected to each ofsaid first jaw members, means mounting each of said arms for limitedarcuate movement from a latching position to an unlatching positioncorresponding to the positions of said first jaw members, and means tomove each of said arms from its latching position to its unlatchingposition thereby also moving a connected first jaw member from itslatching position to its unlatching position, said moving meansincluding an air cylinder and means to supply air to the opposite endsof said cylinder to thereby move said moving means to and from aposition for moving said arm and being located adjacent the end of theline so as to cause the unlatching of the end table from its adjacenttable, and means located along the path of movement for actuating saidmoving means.

2. Plate glass grinding and polishing apparatus, as

recited in claim 1, wherein "said means to supply air to the oppositeends of said cylinder are solenoid valves.

3. Plate glass grinding and polishing apparatus, as recited in claim 2,wherein said actuating means are spaced limit switches for energizingsaid solenoid valves and further including arm means operativelyassociated with said tables for operating said limit switches.

4. Plate glass grinding and polishing apparatus, as recited in claim 3,wherein one of said limit switches is so constructed and arranged toenergize one of said solenoid valves to supply air to one end of saidcylinder to move said moving means and said arm to its unlatchingposition and another of said limit switches is so constructed andarranged to supply air to the opposite end of said cylinder to move saidmoving means to a position of rest.

5. In apparatus for grinding and polishing plate glass, the combinationof a plurality of tables for supporting and conveying sheets of glassalong a grinding and polishing line and having a path of movement alongthe line, interengaging locking means operatively associated with saidtables for locking adjacent tables together, an arm operativelyconnected to said locking means and movable in one direction to unlocksaid locking means, an air cylinder located adjacent the end of the linefor moving said arm in said one direction to unlock said locking meansand thereby unlock a table from an adjacent table upon its arrival atthe end of the line, a source of air under pressure, a valve forcontrolling the flow of air from said source to said cylinder, and meanslocated along said path of movement actuated by said arm for actuatingsaid valve to provide a flow of air from said source to said cylinder tomove said arm in said one direction.

References Cited in the file of this patent UNITED STATES PATENTS1,679,472 Hitchcock Aug. 7, 1928 1,861,659 Fox June 7, 1932 1,901,511Handy Mar. 14, 1933 1,913,994 Price June 13, 1933

